Oxytocin promotes affiliative behaviors and enhances the ability of animals to discriminate between individuals of their own species. The amygdala plays a central role in establishing the social and emotional significance of social stimuli including faces and facial expressions. The central hypothesis of this project is that the oxytocin-induced changes at the behavioral level result from cellular changes in the amygdala, which contains a large concentration of oxytocin receptors. We propose that oxytocin facilitates prosocial behavior by (1) increasing attention directed to social stimuli, particularly the eyes of conspecifics and enhancing the activity of anygdala neurons in response to fixations to the eyes and by (2) enhancing the discrimination of social stimuli through enhanced neural selectivity in the amygdala for face identity and facial expressions. These hypotheses will be tested by recording the activity of multiple single neurons along with the local field potential in the amygdala of monkeys exposed to videos that simulate socio-emotional interactions with other monkeys. It is expected that oxytocin, administered intranasally or by microinjection into the ventricles, will induce behavioral and neural changes that reflect enhanced attention to the eyes and faces, higher individuation of faces, and a processing bias for affiliative stimuli. By examining the effects of oxytocin on neural activity in the amygdala, the proposed experiments will provide a comprehensive test of the hypothesis that oxytocin enhances social cognition via a direct effect on single neurons and networks of neurons in the amygdala. Further, the proposed experiments have the exciting potential outcome of enabling a more detailed and mechanistic understanding of higher cognitive processes involved in primate social behavior, which is critical for the development of better treatments for humans with impairments in social cognition.